Quantity of phenibut in dietary supplements before and after FDA warnings.
Lab testing found phenibut supplements containing anywhere from 21 mg to over 1,100 mg per serving with no way to tell from the label — how would either of us know what dose I've actually been taking?
Suggestive but preliminary. Not settled. how we score evidence
Caveat on this rating: Only four brands met the inclusion criteria, so this is a small snapshot rather than a market-wide survey; it demonstrates that labelled dose cannot be trusted, not the exact proportion of products that are mislabelled.
Phenibut has never been approved by the FDA for any medical use in the United States and is not a lawful dietary supplement ingredient: the FDA has stated that phenibut does not meet the statutory definition of a dietary ingredient, that products listing it as one are misbranded, and it issued
Researchers bought four brands of supplements labelled as containing phenibut before and after the FDA's 2019 warnings and analysed them by mass spectrometry. Before the warnings only two of four actually contained phenibut; afterwards all four did, at 21 mg to 1,164 mg per serving — up to 450% more than a 250 mg Russian pharmaceutical tablet — and the quantity had increased in three of the four products.
Worth asking
Lab testing found phenibut supplements containing anywhere from 21 mg to over 1,100 mg per serving with no way to tell from the label — how would either of us know what dose I've actually been taking?
Source
Quantity of phenibut in dietary supplements before and after FDA warnings. — Cohen PA, Ellison RR, Travis JC, Gaufberg SV, Gerona R. (2022)
Reputable peer-reviewed journal
Read the source: https://doi.org/10.1080/15563650.2021.1973020
DOI: 10.1080/15563650.2021.1973020
How this was scored
- Study design
- Cross-sectional study / survey
- Funding
- Funding not disclosed
- Published in
- Reputable peer-reviewed journal
- Sample size
- 4
- Preregistered
- No
- Conflicts disclosed
- No
- Independent of proponent
- Yes
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published August 19, 2026.
Where we put this study in context
Questions
How strong is the evidence behind this?
Resolv rates this source "early signal". Suggestive but preliminary. Not settled. It scores 42 out of 100 on our published rubric. One caveat travels with that badge: Only four brands met the inclusion criteria, so this is a small snapshot rather than a market-wide survey; it demonstrates that labelled dose cannot be trusted, not the exact proportion of products that are mislabelled. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Quantity of phenibut in dietary supplements before and after FDA warnings. — Cohen PA, Ellison RR, Travis JC, Gaufberg SV, Gerona R. (2022). Published in: Reputable peer-reviewed journal. DOI: 10.1080/15563650.2021.1973020. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Cross-sectional study / survey. Funding: Funding not disclosed. The researchers were independent of whoever benefits from the result. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is phenibut, noofen, anvifen, fenibut, beta-phenyl-gaba, 4-amino-3-phenylbutyric acid, phenygam FDA approved for this use?
No. Its current status is: Not FDA-evaluated for this use. Phenibut has never been approved by the FDA for any medical use in the United States and is not a lawful dietary supplement ingredient: the FDA has stated that phenibut does not meet the statutory definition of a dietary ingredient, that products listing it as one are misbranded, and it issued
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.